This invention relates to substituted benzylaminopiperidine compounds of interest to those in the field of medical chemistry and chemotherapy. More particularly, it is concerned with a series of substituted piperidine compounds, including their pharmaceutically acceptable salts, which are of special value in view of their ability to antagonize substance P. These compounds are of use in treating a gastrointestinal disorder, a central nervous system (CNS) disorder, an inflammatory disease, emesis, urinary incontinence, pain, migraine, sunburn, angiogenesis diseases, disorders and adverse conditions caused by Helicobacter pylori, or the like, especially CNS disorders in a mammalian subject, especially humans.
Substance P is a naturally occurring undecapeptide belonging to the tachykinin family of peptides, the latter being so-named because of their prompt stimulatory action on smooth muscle tissue. More specifically, substance P is a pharmaceutically active neuropeptide that is produced in mammals (having originally been isolated from the gut) and possesses a characteristic amino acid sequence that is illustrated by D. F. Veber et al. in U.S. Pat. No. 4,680,283. The wide involvement of substance P and other tachykinins in the pathophysiology of numerous diseases has been amply demonstrated in the art. For instance, substance P has recently been shown to be involved in the transmission of pain or migraine, as well as in central nervous system disorders such as anxiety and schizophrenia, in respiratory and inflammatory diseases such as asthma and rheumatoid arthritis, respectively, and in gastrointestinal disorders and diseases of GI tract, like ulcerative colitis and Crohn""s diseases, etc. It is also reported that the tachykinin antagonists are useful for the treatment of allergic conditions, immunoregulation, vasodilation, bronchospasm, reflex or neuronal control of the viscera and senile dementia of the Alzheimer type, emesis, sunburn and Helicobacter pylori infection.
International Publication No. WO 93/01170, WO 93/00331 and WO 93/11110 disclose a wide variety of piperidine derivatives, as tachykinin antagonists such as substance P antagonists.
The present invention provides substituted piperidine compounds of the following chemical formula (I): 
and its pharmaceutically acceptable salts, wherein
R is halo C1-C8 alkyl, halo C2-C8 alkenyl, halo C2-C8 alkyl substituted by hydroxy or C1-C8 alkoxy; R1 is hydrogen, halo or C1-C6 alkoxy; or
R and R1, together with the two carbon atoms shared between the benzene ring and the R and R1, complete a fused C4-C6 cycloalkyl wherein one carbon atom is optionally replaced by oxygen and wherein one or two of the carbon atoms are optionally substituted by up to five substituents selected from halo, C1-C6 alkyl and halo C1-C6 alkyl;
X is C1-C6 alkoxy, halo C1-C6 alkoxy, phenoxy or halo; and
Ar is phenyl optionally substituted by halo.
The piperidine compounds of the present invention of formula (I) exhibit good antagonist activity toward Substance P, particularly good activity against CNS disorders, and are thus useful for treatment of a gastrointestinal disorder, a central nervous system disorder, an inflammatory disease, emesis, urinary incontinence, pain, migraine, sunburn, angiogenesis diseases or disorders and adverse conditions caused by Helicobacter pylori in a mammalian subject, especially humans.
Accordingly, the present invention provides a pharmaceutical composition for the treatment of a gastrointestinal disorder, a central nervous system disorder, an inflammatory disease, emesis, urinary incontinence, pain, migraine, sunburn, angiogenesis a diseases, disorders and adverse conditions caused by Helicobacter pylori, or the like, especially CNS disorders in a mammalian subject, especially humans, which comprises a therapeutically effective amount of a compound of the formula (I) together with a pharmaceutically acceptable carrier.
In this specification,
the term xe2x80x9chalo C1-C8 alkylxe2x80x9d is used herein to mean a straight, branched or cyclic C1-C8 alkyl radical substituted with one or more halogens (i.e., Cl, F, I or Br) including, but not limited to, trifluoromethyl, difluoroethyl, trifluoroethyl, pentafluoroethyl, trifluoroisopropyl, tetrafluoroisopropyl, pentafluoroisopropyl, hexafluoroisopropyl or heptafluoroisopropyl and the like;
the term xe2x80x9chalo C2-C8 alkenylxe2x80x9d is used herein to mean a straight, branched or cyclic C2-C8 alkenyl radical substituted with one or more halogens (i.e., Cl, F, I or Br) including, but not limited to, 3,3,3-trifluoropropenyl, 1,1-dimethyl-4,4,4-trifluorobutenyl and the like;
the term xe2x80x9chalo C2-C8 alkynylxe2x80x9d is used herein to mean a straight, branched or cyclic C2-C8 alkynyl radical substituted with one or more halogens (i.e., Cl, F, I or Br) including, but not limited to, 3,3,3-trifluoropropynyl, 1,1-dimethyl-4,4,4-trifluorobutynyl and the like; and
the term xe2x80x9chalo C2-C8 alkoxyxe2x80x9d is used herein to mean a straight, branched or cyclic C1-C8 alkoxy radical substituted with one or more halogens (i.e., Cl, F, I or Br) including, but not limited to, difluoromethoxy, trifluoromethoxy, 2,2,2-trifluoroethoxy and the like.
In the chemical formula (I):
R is preferably C1-C6 alkyl, hydroxy C1-C6 alkyl, C2-C6 alkenyl or C2-C6 alkynyl, wherein the alkyl, alkenyl and alkynyl moieties are substituted by two to seven halogen atoms.
In preferable embodiment of the present invention, R is C1-C6 alkyl, hydroxy C1-C6 alkyl, C2-C6 alkenyl or C2-C6 alkynyl, preferably C1-C6 alkyl, these groups being substituted by two to three fluorine atoms. Examples of R are trifluoromethyl, difluoroethyl, trifluoroethyl, trifluoroisopropyl, trifluoro-tert-butyl, trifluoro-1,1-dimethylmethyl-3-butynyl, and 2chlorotrifluoroisopropyl.
In another preferable embodiment of the present invention, R is C1-C6 alkyl, hydroxy C1-C6 alkyl, C2-C6 alkenyl or C2-C6 alkynyl, these groups being substituted by four to seven fluorine atoms. Examples of R are pentafluoroethyl, pentafluoropropyl, pentafluoroisopropenyl, hexafluoroisopropyl, heptafluoroisopropyl, hexafluoro-2-hydroxyisopropyl and hexafluoro-tert-butyl.
R1 is preferably hydrogen or methoxy, more preferably hydrogen.
In another preferable embodiment of the present invention, R and R1 may be taken together with the two carbon atoms shared between the benzene ring and the R and R1, to complete fused C4-C6 cycloalkyl wherein one carbon atom is optionally replaced by oxygen. The one or two of the carbon atoms of the C4-C6 cycloalkyl may be optionally substituted by up to four, more preferably one to two, substituents selected from a fluorine atom and trifluoromethyl. More preferably, R and R1, may be taken together with the two carbon atoms shared between the benzene ring and the R and R1, complete trifluoromethylcyclopentyl, trifluoromethylcyclohexyl, difluorocyclohexyl or difluorodimethylcyclohexyl.
X is preferably halo, methoxy, difluoromethoxy, trifluoromethoxy or phenoxy, more preferably methoxy, difluoromethoxy or trifluoromethoxy, most preferably methoxy. X is preferably at 2-position on the phenyl ring.
Ar is preferably phenyl.
Another preferred group of compounds of this invention includes the compounds of formula (Ia): 
wherein R1 is hydrogen, halo or methoxy; and R2 and R3 is independently selected from halo, C1-C6 alkyl, C2-C6alkenyl and C2-C6 alkynyl, or R2 and R3 together complete C2-C6 alkylidene, wherein the alkyl, alkenyl, alkynyl and alkylidene moiety are optionally substituted by up to seven halogen atoms;
or R1 and R2 are taken together to complete a fused C4-C6 cycloalkyl wherein one carbon atom is optionally replaced by oxygen, the C4-C6 cycloalkyl being optionally substituted by up to four substituents selected from halo, C1-C4 alkyl, and halo C1-C4 alkyl.
In these compounds, preferable stereochemistry of 2-aryl and 3-benzylamino is (2S,3S).
A preferred group of individual compounds of this invention are the following:
(2S,3S)-3-(2-Fluoro-5-(trifluoromethyl)benzyl)amino-2-phenylpiperidine or its salts;
(2S,3S)-3-(2-Chloro-5-(trifluoromethyl)benzyl)amino-2-phenylpiperidine or its salts;
(2S,3S)-3-(2-Methoxy-5-(trifluoromethyl)benzyl)amino-2-phenylpiperidine or its salts;
(2S,3S)-3-(2-Phenoxy-5-(trifluoromethyl)benzyl)amino-2-phenylpiperidine or its salts;
(2S,3S)-3-(5-(1,1-Difluoroethyl)-2-(trifluoromethoxy)benzyl)amino-2-phenylpiperidine or its salts;
(2S,3S)-3-(5-(1,1-Difluoroethyl)-2-methoxybenzyl)amino-2-phenylpiperidine or its salts;
(2S,3S)-3-(2-Methoxy-5-(2,2,2-trifluoroethyl)benzyl)amino-2-phenylpiperidine or its salts;
(2S,3S)-3-(2-Methoxy-5-(1-(trifluoromethyl)ethyl)benzyl)amino-2-phenylpiperidine or its salts;
(2S,3S)-3-[5-(1,1-dimethyl-4,4,4-trifluoro-2-butynyl)-2-methoxybenzyl]amino-2-phenylpiperidine or its salts;
(2S,3S)-3-[5-(1,1-Dimethyl-2,2,2-trifluoroethyl)-2-methoxybenzylamino]-2-phenylpiperidine or its salt;
(2S,3S)-3-(2,4-Dimethoxy-5-(2,2,2-trifluoroethyl)benzyl)amino-2-phenylpiperidine or its salts; and
(2S,3S)-3-[5-(1-Chloro-1-trifluoromethyl-ethyl)-2-methoxybenzylamino]-2-phenylpiperidine; or its salts.
Another preferred group of individual compounds of this invention are the following:
(2S,3S)-2-Phenyl-3-(5-(2,2,2-trifluoro-1-(trifluoromethyl)ethyl)-2-methoxybenzyl)aminopiperidine or its salts;
(2S,3S)-2-Phenyl-3-(5-(2,2,2-trifluoro-1-(trifluoromethyl)ethyl)-2-methoxybenzyl)aminopiperidine or its salts;
(2S,3S)-2-Phenyl-3-(5-(1,2,2,2-tetrafluoro-1-(trifluoromethyl)ethyl)-2-methoxybenzyl)aminopiperidine or its salts;
(2S,3S)-3-(2-Methoxy-5-(1,1,2,2,2-pentafluoroethyl)benzyl)amino-2-phenylpiperidine or its salts;
(2S,3S)-2-Phenyl-3-(5-(2,2,2-trifluoro-1-methyl-1-(trifluoromethyl)ethyl)-2-methoxybenzyl)aminopiperidine or its salts;
(2S,3S)-3-[5-[2,2-Difluoro-1-(trifluoromethyl)ethenyl]-2-methoxy benzyl]amino-2-phenylpiperidine or its salts; and
(2S,3S)-3-(2-Methoxy-5-(2,2,2-trifluoro-1-hydroxy-1-(trifluoromethyl)ethyl)benzyl)amino-2-phenylpiperidine or its salts.
Another preferred group of individual compounds of this invention are the following:
[(2S,3S)-3-[5-Methoxy-1-trifluoromethyl-indan-6-yl-methylamino]-2-phenylpiperidine.
(2S,3S)-3-[6-Methoxy-1-trifluoromethyl-1,2,3,4-tetrahydronaphthalen-7-yl-methylamino]-2-phenylpiperidine.
(2S,3S)-3-((2,2-Difluoro-6-methoxy-1,2,3,4-tetrahydronaphthalen-7-yl)methyl)amino-2-phenylpiperidine or its salts.
The piperidine compounds of the formula (I) of this invention may be prepared as described in the following reaction schemes.
Unless otherwise indicated, in the reaction schemes that follow, R, X and Ar are defined as above. 
Scheme A-I illustrates a method for preparing compounds of the formula (I) by reductive amination of a compound of the formula (III) with a compound (II). The reduction can be carried out by catalytic hydrogenation, or with several hydride reagents in a reaction-inert solvent. The catalytic hydrogenation may be carried out in the presence of a metal catalyst such as palladium or Raney nickel. Suitable hydride reagents include borohydrides such as sodium borohydride (NaBH4), sodium cyanoborohydride (NaBH3CN) and sodium triacetoxyborohydride (NaB(OAc)3H), boranes, aluminum-based reagents and trialkylsilanes. Suitable solvents include polar solvents such as methanol, ethanol, methylene chloride, tetrahydrofuran (THF), dioxane and ethylacteate. This reaction is typically carried out at a temperature from xe2x88x9278xc2x0 C. to reflux temperature of the solvent, preferably from 0xc2x0 C. to 25xc2x0 C. for 5 minutes to 48 hours, preferably from 0.5 to 12 hours.
Alternatively, the piperidine compounds of the formula (I) of this invention may be prepared as shown in the following scheme A-II. 
(wherein Z is a leaving group such as halo or sulfonate including tosylate or mesylate)
Referring to Scheme A-II, the compounds of the formula (I) of this invention may be prepared by a reaction of a compound of the formula (I) with a compound (II). The compound (IV) may be treated with compound (II) in the presence of a base (e.g., K2CO3 or Na2CO3) in a polar solvent (e.g., methanol, ethanol, isopropylalcohol, THF, dioxane, dimethylformamide (IMF) or dimethylsulfoxide (DMSO). This reaction is typically carried out at a temperature from xe2x88x9278xc2x0 C. to reflux temperature of the solvent, preferably from 0xc2x0 C. to 25xc2x0 C. for 5 minutes to 48 hours, preferably from 0.5 to 12 hours.
The compounds (IV) may be prepared by reduction of an aldehyde of the formula (III), followed by conversion of a hydroxy group of the resultant compound into a leaving group, Z. Reduction of the aldehyde (III) may be accomplished using a variety of reducing agents in a reaction-inert solvent. Suitable reducing agent/solvent systems include sodium tetrahydroborate (NaBH4) in methanol or ethanol; lithium tetrahydroborate (LiBH4) in THF or diethyl ether; lithium tetrahydroaluminum (LiAlH4), lithium triethoxyhydroaluminum (LiAl(OEt)3H) lithium tert-buthoxyhydroaluminum (LiAl(OBut)3H) or aluminum trihydride (AlH3) in THF or diethyl ether; and iso-butyl aluminum hydride(i-BuAlH2) or diisopropyl aluminum hydride (DIBAL-H) in dichloromethane, THF or n-hexane. This reaction is generally carried out at a temperature from xe2x88x9220xc2x0 C. to 25xc2x0 C. for 5 minutes to 12 hours. Then, the hydroxy group of the resultant compound is converted to a leaving group, Z (e.g., halo such as chloro, bromo, iodo or fluoro, or sulfonate including tosylate or mesylate). Conversion of the hydroxy group into the leaving group, Z may be accomplished according to methods known to those skilled in the art. For example, when Z is sulfonate such as tosylate or mesylate, the hydroxy compound is reacted with sulfonate in the presence of pyridine or triethylamine in dichloromethane. When Z is halo such as chloro or bromo, the hydroxy compound may be treated with SOX2 (X is Cl or Br) in the presence of pyridine.
The compounds of the formula (III) can be prepared as illustrated in the following scheme B-I. 
The compounds of the formula (II) may be prepared by direct or indirect formylation of a compound of the formula (V). Any formylation methods known to those skilled in the art may be used, to introduce a formyl group into a benzene ring. For example, direct formylation may be accomplished by contacting the compound (V) with a suitable formylating agent in the presence of a suitable catalyst. Suitable formylating agent/catalyst systems include dichloromethyl methyl ether/titanium (IV) chloride (Cl2CHOCH3/TiCl4), trifluoroacetic acid (CF3CO2H)/hexamethylenetetramine (modified Duff""s conditions) and phosphoryl trichloride (POCl3)/DMF (Vilsmeier""s conditions). Indirect formylation may be achieved by halogenating the compound (V), displacing the halogen atom introduced with a cyano group, and then subjecting the resultant cyano-substituted compound to reduction. The halogenation as used herein may be carried out according to the procedure reported in G. A. Olah et., al. J. Org Chem, 58, 3194 (1993). The displacement of the halogen atom with a cyano group may be performed according to the methods reported in D. M. Tschaem et. al., Synth Commun. 24, 887 (1994), K. Takagi et. al., 64 Bull Chem. Soc. Jpn. 64, 1118 (1991). The reduction as used herein may be performed in the presence of diisopropyl aluminiumhydride (DIBAL-H) in dichloromethane or Raney nickel in formic acid.
The starting materials of the formula (V) are known compounds which are commercially available, or can be prepared by known methods. For example, compounds of the formula (V) wherein X is alkoxy can be prepared by O-alkylation of the corresponding compounds (V) wherein X is hydroxy, in the presence of a base (e.g., NaH or KH) in a suitable solvent (e.g., DMSO, DMF and THF).
Compound (V) can be also prepared by other methods as described in the following literature:
(A) trifluoromethylation, J. Am. Chem Soc., 111, 393-395 (1989);
(B) tert-alkylation, Angew. Chem. Int. Ed. Engl. 19, No.11 900-901 (1980); or
(C) chemoselective and position specific methylation of tert-alkyl halides with methyltitanium (IV), Angew. Chem. Int. Ed. Engl. 19, No.11 901-902 (1980) and fluorination of keton, Organic Reaction (1988), 35
In addition, R in the compound of formula ( can be converted to any desirable substituent Rxe2x80x3 (e.g., CF2CF3 or CF2CH3) according to techniques known to a person skilled in the art, for example, as indicated in the following Scheme B-II. 
In Scheme B-II, the starting materials of the formula (VI) are known compounds which can be prepared according to the procedures described in, for example Collect. Czech. Chem. Commun., 52, 980 (1987) or Bull. Chem. Soc. Jpn., 51, 2435 (1978).
For example, a compound of formula (VI) wherein A is CN and R is allylcarbonyl (see Collect. Czech. Chem. Commun., 52, 980 (1987)) may be subjected to thioketalization followed by substitution to obtain a compound of formula (VII) (see J. Org. Chem., 51, 3508 (1986)). A compound of formula (VI) wherein A is acetal and R is halo (see Bull. Chem. Soc. Jpn., 51, 2435 (1978)) may be subjected to alkylation to obtain a compound of formula (VII) (see Synthetic Comm., 18, 965 (1988)).
Then the compound of formula (VII) may be subjected to solvolysis or reduction under suitable reaction conditions to obtain a compound of formula (VIII) wherein R is converted to Rxe2x80x3 (e.g., CF2CF3 or CF2CH3) (see J. Org. Chem, 24, 627 (1959) and Protective group in organic synthesis, John Wiley and sons, inc., 180 and 191 (1991)).
Alternatively, compounds of the formula (I) may be prepared as shown in the following Scheme A-III. 
Scheme A-IlI illustrates the preparation of compounds of the formula (I). Referring to Scheme A-III, N-protection of a compound of the formula (IX) (Ar is phenyl or the like) may be carried out by treatment with (t-BuOCO)2O (Boc2O) in the presence of a base such as sodium bicarbonate (NaHCO3) or triethylamine (Et3N) to obtain a compound of the formula (X). Compound (X) is subjected to hydrogenolysis to obtain a compound of the formula (XI) (wherein Ar is phenyl). An alternative route for N-protection of a compound of the formula (IX) may be carried out by treatment with carbobenzoxy chloride (Cbz-Cl) in the presence of a base such as sodium bicarbonate (NaHCO3) or triethylamine (Et3N), wherein Ar is phenyl. The hydrogenolysis may be carried out by treatment with H2 or ammonium formate (HCO2NH4) in the presence of a metal catalyst such as a palladium on charcoal (e.g. 20% palladium on charcoal) in a suitable solvent. Then, the compound (XI) is subjected to the reductive amination as described in Scheme A-I. The compound (XII) may be converted into a compound of the formula (I) by treatment with acid catalyst such as hydrochloride (HCl) in methanol, conc.HCl in ethylacetate or CF3CO2H in dichloroethane.
The compounds of formula (I), and the intermediates shown in the above reaction schemes can be isolated and purified by conventional procedures, such as recrystallization or chromatographic separation.
As the piperidine compounds of this invention possess at least two asymmetric centers, they are capable of occurring in various stereoisomeric forms or configurations. Hence, the compounds can exist in separated (+)- and (xe2x88x92)-optically active forms, as well as mixtures thereof. The present invention includes all such forms within its scope. Individual isomers can be obtained by known methods, such as optical resolution, optically selective reaction, or chromatographic separation in the preparation of the final product or its intermediate.
In so far as the piperidine compounds of this invention are basic compounds, they are all capable of forming a wide variety of different salts with various inorganic and organic acids. Although such salts must be pharmaceutically acceptable for administration to animals, it is often desirable in practice to initially isolate the piperidine base compound from the reaction mixture as a pharmaceutically unacceptable salt and then simply convert to the free base compound by treatment with an alkaline reagent and thereafter convert the free base to a pharmaceutically acceptable acid addition salt. The acid addition salts of the piperidine base compounds of this invention are readily prepared by treating the base compound with a substantially equivalent amount of the chosen mineral or organic acid in an aqueous solvent or in a suitable organic solvent, such as methanol or ethanol. Upon careful evaporation of the solvent, the desired solid salt is readily obtained. The acid which are used to prepare the pharmaceutically acceptable acid addition salts of the aforementioned piperidine base compounds of this invention are those which form non-toxic acid addition salts, i.e., salts containing pharmaceutically acceptable anions, such as the hydrochloride, hydrobromide, hydroiodide, nitrate, sulfate or bisulfate,phosphate or acid phosphate, acetate, lactate, citrate or acid citrate, tartrate or bi-tartrate, succinate, maleate, fumarate, gluconate, saccharate, benzoate, methanesulfonate, ethanesulfonate, benzenesulfonate, p-toluenesulfonate and pamoate (i.e., 1.1xe2x80x2-methylene-bis-(2-hydroxy-3-naphthoate))salts.
The piperidine compounds of the invention which have also acidic groups are capable of forming base salts with various pharmaceutically acceptable cations. Examples of such salts include the alkali metal or alkaline-earth metal salts and particularly, the sodium and potassium salts. These salts are all prepared by conventional techniques.
The chemical bases which are used as reagents to prepare the pharmaceutically acceptable base salts of this invention are those which form non-toxic base salts with the herein described acidic piperidine derivatives. These particular non-toxic base salts include those derived form such pharmaceutically acceptable cations as sodium, potassium, calcium and magnesium, etc. These salts can easily be prepared by treating the aforementioned acidic piperidine compounds with an aqueous solution containing the desired pharmaceutically acceptable cation, and then evaporating the resulting solution to dryness, preferably under reduced pressure. Alternatively, they may also be prepared by mixing lower alkanoic solutions of the acidic compounds and the desired alkali metal alkoxide together, and then evaporating the resulting solution to dryness in the same manner as before. In either case, stoichiometric quantities of reagents are preferably employed in order to ensure completeness of reaction and maximum production of yields of the desired final product.
The active piperidine compounds of the present invention exhibit significant substance P receptor-binding activity and therefore, are of value in the treatment of a wide variety of clinical conditions which are characterized by the presence of an excess of said substance P activity. Such conditions include gastrointestinal disorders, central nervous system disorders, inflammatory diseases, emesis, urinary incontinence, pain, migraine or angiogenesis in a mammalian subject, especially humans. For treatment of emesis, these compounds may preferably be used in combination with a 5HT3 receptor antagonist.
The active piperidine compounds of the formula (I) of this invention can be administered via either the oral, parenteral or topical routes to mammals. In general, these compounds are most desirably administered to humans in doses ranging from about 0.3 mg up to 750 mg per day, although variations will necessarily occur depending upon the weight and condition of the subject being treated and the particular route of administration chosen. However, a dosage level that is in the range of from about 0.06 mg to about 2 mg per kg of body weight per day is most desirably employed. Nevertheless, variations may still occur depending upon the species of animal being treated and its individual response to said medicament, as well as on the type of pharmaceutical formulation chosen and the time period and interval at which such administration is carried out. In some instances, dosage levels below the lower limit of the aforesaid range may be more than adequate, while in other cases still larger doses may be employed without causing any harmful side effects provided that such higher dose levels are first divided into several small doses for administration throughout the day.
The compounds of the present invention may be administered alone or in combination with pharmaceutically acceptable carriers or diluents by either of the above routes previously indicated, and such administration can be carried out in single or multiple doses. More particularly, the novel therapeutic agents of the invention can be administered in a wide variety of different dosage forms, i.e., they may be combined with various pharmaceutically acceptable inert carriers in the form of tablets, capsules, lozenges, trochees, hard candies, powders, sprays, creams, salves, suppositories, jellies, gels, pastes, lotions, ointments, aqueous suspensions, injectable solutions, elixirs, syrups, and the like. Such carriers include solid diluents or fillers, sterile aqueous media and various nontoxic organic solvents, etc. Moreover, oral pharmaceutical compositions can be suitably sweetened and/or flavored. In general, the therapeutically-effective compounds of this invention are present in such dosage forms at concentration levels ranging about 5.0% to about 70% by weight.
For oral administration, tablets containing various excipient such as microcrystalline cellulose, sodium citrate, calcium carbonate, dicalcium phosphate and glycine may be employed along with various disintegrants such as starch and preferably corn, potato or tapioca starch, alginic acid and certain complex silicates, together with granulation binders like polyvinylpyrrolidone, sucrose, gelatin and acacia. Additionally, lubricating agents such as magnesium stearate, sodium lauryl sulfate and talc are often very useful for tabletting purposes. Solid compositions of a similar type may also be employed as fillers in gelatine capsules; preferred materials in this connection also include lactose or milk sugar as well as high molecular weight polyethylene grycols. When aqueous suspensions and/or elixirs are desired for oral administration, the active ingredient may be combined with various sweetening or flavoring agents, coloring matter or dyes, and, if so desired, emulsifying and/or suspending agents as well, together with such diluents as water, ethanol, propylene glycol, glycerin and various like combinations thereof.
For parenteral administration, solutions of a compound of the present invention in either sesame or peanut oil or in aqueous propylene glycol may be employed. The aqueous solutions should be suitably buffered (preferably pH greater than 8) if necessary and the liquid diluent first rendered isotonic. These aqueous solutions are suitable for intravenous injection purposes. The oily solutions are suitable for intra-articular, intra-muscular and subcutaneous injection purposes. The preparation of all these solutions under sterile conditions is readily accomplished by standard pharmaceutical techniques well-known to those skilled in the art. Additionally, it is also possible to administer the compounds of the present invention topically when treating inflammatory conditions of the skin and this may preferably be done by way of creams, jellies, gels, pastes, ointments and the like, in accordance with standard pharmaceutical practice.
The activity of the compounds of the present invention, as substance P antagonists, is determined by their ability to inhibit the binding of substance P at its receptor sites in CHO-cells which reveal NK1 receptor or IM-9 cells employing radioactive ligands. The substance P antagonist activity of the herein described piperidine compounds is evaluated by using the standard assay procedure described by M. A. Cascieri et al., as reported in The Journal of Immunology, 133, 3260 (1984). This method essentially involves determining the concentration of the individual compound required to reduce by 50% the amount of radiolabelled substance P ligands at their receptor sites in said isolated cow tissues or IM-9 cells, thereby affording characteristic IC50 values for each compound tested. More specifically, inhibition of [3H]SP binding to human IM-9 cells by compounds are determined in assay buffer (50 mM Tris-HCl (pH 7.4), 1 mM MnCl2, 0.02% bovine serum albumin, bacitracin (40 xcexcg/ml), leupeptin (4 xcexcg/ml), chymostatin (2 xcexc/ml) and phosphoramidon (30 xcexcg/ml)). The reaction is initiated by the addition of cells to assay buffer containing 0.56 nM [3]SP and various concentrations of compounds (total volume; 0.5 ml) and allowed to incubate for 120 min at 4xc2x0 C. Incubation is terminated by filtration onto GF/B filters (presoaked in 0.1% polyethylenimine for 2 hours). Nonspecific binding is defined as the radioactivity remaining in the presence of 1 xcexcM SP. The filters are placed into tubes and counted using liquid scintillation counter.
The adverse effect on Ca2+ channel binding affinity is determined by study of verapamil binding in a rat heart membrane preparation. More specifically, verapamil binding is performed as previously described by Reynolds et al., (J. Pharmacol. Exp. Ther. 237, 731, 1986). Briefly, incubations are initiated by the addition of tissue to tubes containing 0.25 nM [3H]desmethoxyverapamil and various concentrations of compounds (total volume; 1 ml). Nonspecific binding is defined as radioligand binding remaining in the presence of 3-10 xcexcM methoxyverapamil.
The activity of the compounds of this invention against CNS disorders is determined in a [Sar9, Met(O2)11]substance P-induced tapping test in gerbils. More specifically, gerbils are lightly anesthetized with ether and the skull surface is exposed. [Sar9, Met(O2)11]substance P or vehicle (5 xcexcl) are administered directly into the lateral ventricles via a 25 gauge needle inserted 3.5 mm below lambda. Following injection, gerbils are placed in 2 l beaker individually and monitored for repetitive hind paw tapping. Some compounds prepared in the following Examples were tested in accordance with these testing methods. As a result, it was found that the compounds of the present inventions have good antagonist activity toward Substance P, particularly good activity against CNS disorders with favorable metabolical properties. More specifically, for example, by comparing trifluoromethyl- and hexafluoroisopropyl-benzylaminopiperidine compounds (Examples 3 and 5, respectively) with the corresponding no halosubstituted compounds, it was found that the halo-substituted compounds showed unexpectedly improved activity against CNS disorders.
The half life of the compounds of this invention is determined in a human liver microsome preparation. More specifically, the compound (1 xcexcM) was incubated with pooled human liver microsome (2.0 mg/ml), NADP (1.3 mM), NADH (0.93 mM), glucose-6-phosphate (3.3 mM) MgCl2 (3.3 mM), and glucose-6-phosphate dehydrogenase (8 units/ml) in a total volume of 1.2 ml 100 mM potassium phosphate buffer, pH 7.4. At various time points (0, 5, 10, 30 and 60 min), a 100 xcexcl sample was added to acetonitrile solution (1.0 ml), which included an internal standard. The precipitated protein was spun down in a centrifuge (3,000xc3x97g, 5 min). The supernatant w as analyzed by LC-MS. LC-MS unit was consisted of Hewlett Packard HP1090 HPLC system and Sciex API-III. Samples(10 xcexcl) were injected by means of autosampler, onto Hewlett Packard ODS-Hypersil column (2.1xc3x9720 mm). A mobile phase was consisted of 80% acetonitrile in 10 mM ammonium acetate. The measurement of API-III was analyzed with multiple reacting monitoring (MRM) detection.